Truss style Gantry

[Jonathan]

I had thought about that but I was getting concerned with the weight
...
Do the struts really need the mass of the main beams or were you suggesting that for ease of construction?

I wouldn't worry about the weight too much from the point of view of the stepper motor(s). Try using irving's motor calculation spreadsheet and you'll see how little difference an extra 20kg out of 80kg will make. I was just suggesting it for ease of construction but there is no reason to assume I meant make all the box section the same size.

[D.C.]

I wouldn't worry about the weight too much from the point of view of the stepper motor(s). Try using irving's motor calculation spreadsheet and you'll see how little difference an extra 20kg out of 80kg will make. I was just suggesting it for ease of construction but there is no reason to assume I meant make all the box section the same size.

I sort of ended up with the odd mix based on what I knew I could do, the bar is there because I have no way of accurately bending steel and I don't think just bashing it with a hammer would get a good enough epoxy joint.

That said I could weld the supports to a mounting plate off the gantry and then epoxy the plates...

The biggest flaw I think is with the rail location, I'm losing travel either side and also won't be able to get the bottom bearings off the rail without removing the whole rail. Hmmmm, back to drawing board.